If you're in Downtown Seattle around noon on Mondays, there's a free 20 minute tour you might want to check out. It's a guided tour of the 5th Avenue Theatre and gives you the chance to see the building's architecture and learn about its history without any crowds around. Please note, you do need to register online for the tour and you may want to check a week ahead of time that the tour is actually taking place (eg. if a show is going on at 12, they don't want a tour group walking across the stage!). Meet under the theatre marquee on 5th and University.